Thread pull-off device for buttonhole sewing machines



J. H. PIKUL 2,076,185 THREAD PULL-OFF DEVICE FOR BUTTONHOLE SEWING MACHINES April 6, 1937.

27, 1934 2 Sheets-Sheet l ln'vnT csr. \Joseph H. P'IKUT Original Filed Oct April 1937- J. H. PIKULI 2,076,185

THREAD PULL-OFF DEVICE FOR BUTTONHOLE SEWING MACHINES Original Filed Oct. 27, 1934 2 Sheets-Sheet 2 Uoseph HPiKUI b fiwpawdm ATTys.

Patented Apr. 6, 1937 UNITED STATES THREAD PULL-OFF DEVICE FOR- BUTTON- HOLE SEWING MACHINES Joseph H. Pikul, Boston,

Reece Button Hole Machine Company,

Mass, assignor to The Boston,

Mass, a corporation of Maine Original application October 2'7, 1934, Serial No. 750,335. Divided and this application July 13, 1935, Serial No. 31,215

5 Claims.

This invention relates to sewing machines of the type adapted to sew a short seam and then come to rest and particularly to a sewing machine of this type which is constructed so that when the short seam is completed. the needle comes to rest in a raised position with a loop of needle thread caught on the under thread mechanism beneath the work, and which is also constructed with means for breaking or disrupting the needle thread beneath the work at the last stitch.

An object of the invention is to provide an improved device for engaging the needle thread between the work and the needle after said thread has been broken or disrupted and pulling the broken end of the needle thread back from the work and holding it until the first stitch has been formed on the next succeeding seam.

In order to give an understanding of the invention I have illustrated in the drawings a selected embodiment thereof which will now be described after which the novel features will be pointed out in the appended claims.

In the drawings:

Fig. 1 is a side view of a sewing machine embodying my invention.

Fig. 2 is an enlarged view showing the thread pull-01f device in position ready to engage the needle thread and pull it back through the cloth.

Fig. 3 is a fragmentary top plan view of the pull-off device.

- Fig. 4 is a fragmentary side view of the thread pull-ofi device looking at it from the opposite side from that shown in Fig. 1.

The sewing machine shown in Fig. 1 is of the usual type having the work frame I for supporting the work 2 in which the short seam is to be sewed, which work frame supports the work clamps 3 for clamping the work in position during the sewing of the seam, and also having the. stitch frame 4 carrying stitch-forming mecha nism, said stitch frame and work frame being movable relative to each other. The stitch-forming mechanism is of the usual type including a vertically-reciprocating needle 5 operating above the work and carried by a needle bar 6 which re'ciprocates in the head portion 1 of the stitch frame and also including under thread mechanism shown diagrammatically at 8 in Fig. 2 and 50 which is preferably in the form of loopers and looper-spreaders carried by the turret 9 which is rotatably mounted in the lower portion ill of the stitch frame. ll indicates the usual main cam by which the operations of the machine are controlled, said cam being rotatably mounted in the cam housing 12 forming part of the stitch frame as usual in sewing machines of this type.

the particular embodiment herein illustrated the relative feeding movement between the stitch 50 frame 4 and work frame I is secured by movement of the stitch frame 4 forwardly and backwardly on the Work frame.

Sewing machines of this type are usually constructed so that the stitch-forming mechanism comes to rest at the completion of each short seam with the needle raised as shown in Figs. 1 and 2 and with a loop l3 of needle thread 14 caught on the under thread mechanism 8 beneath the work.

These sewing machines are also usually provided with some means for disrupting or severing the needle thread beneath the work at the last stitch and one way in which this is frequently accomplished is by providing means for moving the stitch frame forwardly after the stitch-forming mechanism has come to rest, thereby to apply sufficient strain on the needle thread to cause one leg of the loop [3 to break at the last stitch, this being the construction illustrated in my co-pending application Serial No. 750,335, filed October 27, 1934 of which this application is a division.

After the needle thread I4 is thus broken it is necessary to withdraw the broken end from the work before the stitching on the next short seam begins and the present invention relates to a novel means for engaging the needle thread between the needle and the work and withdrawing the broken end of the thread from the work and holding said end until the first stitch isv formed on the succeeding short seam.

This pulling of the needle thread 14 back from the work is accomplished by a pull-off member l5 which is carried by a supporting lever l6 pivotally mounted on the stitch frame at I! and provided with a tail portion I8 adapted to be engaged by a cam hump I9 with which the main cam ll of the machine is provided. The supporting lever I6 is similar to the usual cutter lever in a buttonhole sewing machine, and in fact, if the sewing machine I is of the type designed to sew a short scam in the nature of a buttonhole then the lever It might be the lever carrying the buttonhole cutter for cutting the buttonhole slit. This supporting lever i6 is acted upon by a spring 20 which normally holds it in its raised inoperative position shown in Fig. 1 and the cam hump I9 is so positioned that it will engage the tail is of the lever it just after the stitch-forming mechanism comes to rest, thereby swinging said lever l6 into its lowered position shown in Fig. 2, and

when the cam hump l9 has passed the tail l8 the spring 20 will return the lever IE to its raised position.

The downward movement of the lever it into the position shown in Fig. 2 causes the pull-off member l5 to wipe by the portion of the needle thread It extending from the needle to the work, and the return movement of the lever It to its raised position causes the thread pull-off member to engage the thread I 4 to pull the broken end thereof back through and free from the work.

The pull-off member 15 is provided at its free end with a hooked portion 2| and is also provided with a felt strip 22, the outer end of which engages the inner face of the hooked member 2!. This pull-off member I 5 is pivoted at 23 to one end of a lever 24 which in turn is pivoted intermediate its ends at 25 to the supporting lever I6.

The other end of the lever 24 is pivotally connected at 30 to one end of a link 26, the other end of which link is pivoted to the stitch frame at 21. 28 indicates a spring acting on the pivoted pulloff member l5 and tending to resist upward l5 swinging movement of said pull-off arm relative to the lever 24.

29 indicates a stop or rest carried by the lever l6 and against which the member is yieldingly held by the spring 28.

When the supporting lever 16 is in its normal raised position shown in Figs. 1 and 4 the pulloff finger or member IE will be situated in the rear of the needle as also shown in Figs. 1 and 4. When the supporting lever l6 swings clockwise into its lowered position shown in Fig. 2, the short lever 24 will be turned from the position shown in Fig. 1 to that shown in Fig. 2 by the action of the link 26, and this turning movement will slide the pull-off finger l5 forwardly over .30 the rest 29 into the position shown in Fig. 2, the

spring 28 holding the pull-oif finger in engagement with the rest during such movement. This movement of the pull-off finger carries the hooked end 21 past the needle thread 14 as shown in Fig. 2 into a position in front thereof. The

shape of the hooked portion 2! is such that during its forward movement it will readily wipe by the thread I4 without catching thereon and when the pull-off member is in its forward position it will have a position relative to the thread I4 shown in Figs. 2 and 3.

As the supporting lever l6 swings back into its raised position the pull-off finger l 5 will be given a backward movement into the position shown in Figs. 1 and 4 and during this backward movement the needle thread M is caught by the hook 2| with the result that the broken end of the needle thread will be pulled free from the work 2. During the pulling of the thread l4 free from the 50 work said thread becomes caught between the felt strip 22 and the inner face of the hook 2| and said felt provides sufficient frictional engagement with the thread to hold the end as shown in Figs. 1 and 4. The end of the needle thread will 55 thus be held until the first stitch is formed on the next seam and as soon as this has been accomplished the strain on the thread will pull it free from the pull-off arm.

1. A sewing machine having work-holding 60 means, stitch-forming mechanism including a needle, said stitch-forming mechanism and workholding means having a backward and forward relative movement, a pivotally-mounted lever, means to give said lever an oscillating motion at 65 the end of a sewing operation, a thread pull-off member carried by said lever and having a threadengaging portion normally situated in the rear of the needle, means operative during the swinging movement of said lever in one direction to move 70 the pull-off member relative to said lever forwardly in the direction of said relative movement thereby to carry its thread-engaging portion into a position in front of the needle and operative during the movement of said lever in the opposite direction to move the pull-01f member backwardly thereby causing the thread-engaging portion thereof to engage the needle thread and pull it free from the work.

2. A sewing machine having work-holding means, stitch-forming mechanism including a needle, said stitch-forming mechanism and workholding means having a backward and forward relative movement, a rocking lever situated above the work and movable toward and from the latter, a thread pull-off member mounted on said lever and adapted to move relative thereto in the direction of said relative movement, means to give the lever a movement toward the work and then away from the work at the end of a sewing operation and means connected with said pull-off member togive it a backward movement to engage the thread leading from the needle to the work and pull said thread free from the work during the return movement of said lever.

3. A sewing machine having work-holding means, a stitch frame, stitch-forming mechanism including a needle mounted on said stitch frame, said stitch frame and work-holding means having a backward and forward relative movement, a, lever pivoted to the stitch frame, means to give the lever a movement toward the work and then a reverse movement at the end of the sewing operation, a thread pull-off finger mounted on said lever and adapted to move relative thereto in a forward and backward direction, said finger being normally situated in the rear of the needle, and means to move the thread pull-off finger forwardly during the movement of the lever toward the work and rearwardly during the reverse movement of the lever thereby to cause said pull-off finger to engage the thread between the needle and work and pull it back from the work.

4. A sewing machine having work-holding means, stitch-forming mechanism, a pivotallymounted lever, means operative at the end of the sewing to give the lever a movement toward the work and then a reverse movement, a rocker pivotally mounted on said lever, a pull-off finger pivotally connected to one end of said rocker, and means connecting the other end of said rocker to a fixed support, whereby when the lever moves toward the work the pull-off finger is moved forwardly into position to engage the thread and when the lever has its reverse movement the thread pull-off finger pulls the thread back from the work.

5. A sewing machine having work-holding means, stitch-forming mechanism including a needle, a pivotally-mounted lever, means to give said lever an oscillating motion at the end of a sewing operation, a thread pull-off finger pivotally mounted on said lever to turn about a horizontal axis, means connecting said pull-off finger to a fixed support, said finger having a position in the rear of the needle when said lever is in raised position, said connection operating to swing the pull-off finger forwardly relative to the lever as the latter moves toward the work to move the thread-engaging portion of said finger into a position in front of the needle and to swing said pull-off finger backwardly as the lever is raised, thereby to cause said finger to engage the thread and pull it free from the work.

JOSEPH H. PIKUI 

